Relative Protein Efficiency Ratio Research Articles

Concentrados proteicos vegetais na alimentação de Jundiás (Rhamdia quelen)

O objetivo deste estudo foi avaliar fontes de concentrados proteicos vegetais alternativos em substituição ao farelo de soja sobre o desempenho e composição centesimal de jundiás (Rhamdia quelen) e coloração dos filés. Foram utilizadas 20 unidades experimentais, com capacidade de 90L cada uma, onde 400 peixes permaneceram alojados durante 45 dias. Os juvenis de jundiá possuíam 11,5±5,0cm e peso inicial de 10,4±5,5g. Foram avaliadas quatro fontes de concentrados proteicos, sendo eles: dieta controle, tendo o farelo de soja com base proteica; CL: dieta contendo concentrado proteico de crambe + concentrado proteico de linhaça; CLGM: composta por concentrado proteico de crambe + concentrado proteico de linhaça + concentrado proteico de folha de mandioca + concentrado proteico de farelo de girassol e GM: constituída por concentrado proteico de farelo de girassol + concentrado proteico de folha de mandioca. Aos 30 e 45 dias, foram avaliados os parâmetros de crescimento (peso, fator de condição, taxa de crescimento específico, ganho em peso diário e relativo, taxa de eficiência proteica e conversão alimentar aparente) e avaliação centesimal do peixe inteiro e filé (umidade, proteína bruta, gordura e cinzas). Além disso, aos 45 dias, foi realizada a avaliação instrumental da cor nos filés. Ao final do período experimental, foram observadas diferenças significativas para os parâmetros de crescimento e avaliação centesimal, sendo que os animais alimentados com as dietas CL apresentaram maior crescimento (13,8cm), taxa de crescimento específico (2,43% dia-1), ganho em peso diário (0,41g dia-1), ganho em peso relativo (108,3%) e menor conversão alimentar (1,21), comparado às dietas contendo concentrado proteico de girassol e concentrado proteico de folhas de mandioca. Observou-se também que os animais alimentados com as dietas GM e CLGM apresentaram uma pigmentação amarelada nos filés. Conclui-se que os animais alimentados com a dieta CL obtiveram os maiores índices de desempenhos, podendo ser utilizada como alimento na formulação de dietas para esta espécie. As demais combinações não redundaram em resultados melhores que a dieta controle e CL.

Biological Evaluation of Protein Meals for Making Nutrient Dense Food Bar

2 Abstract: The study was undertaken for biological evaluation of protein meals, differing in raw or processed chickpea (Cicer arietinum L.) and vetch (Lathyrus sativus L.) flour for nutritionally rich food bar making. The indigenous food processing technologies such as controlled and natural fermentation and germination were utilized to improve the protein quality of legumes. The resultant flours were thereafter blended with other protein sources to produce balanced protein meal. The protein quality of these diets was assessed by implying in-vivo rat assays. The values for relative protein efficiency ratio (RPER) and relative net protein ratio (RNPR) in close proximity to each other for processed meals are an indicator of good protein quality of these meals. It could be concluded that food bars with good protein quality can be produced by using meals carrying processed vetch or chickpea.

Variedades de feijão e seus efeitos na qualidade protéica, na glicemia e nos lipídios sangüíneos em ratos

Beans are important source of protein in the Brazilian staple food and may modulate the blood glucose and lipid levels. The objective of this study was to evaluate the protein quality and functional properties of varieties of beans. Seven groups (n = 6) of weaning rats were used for the bean protein quality analysis. The first group was fed protein-free diet for 14 days, and the remaining were fed diets with 9 to 10% protein provided by either casein or one of the 5 varieties of beans (Ouro Perola, BRS Radiante, and Talisma). In a further study, 4 groups (n = 10) of adult rats were fed diets containing either casein or Ouro Branco, Diamante Negro, and Talisma beans (30 g.100 g-1 diet), for 28 days. Ouro Branco, white beans, showed higher relative Protein Efficiency Ratio (rPER = 61.18%) than the other varieties, and the BRS Radiante, brown beans, showed the lowest value (rPER = 44.60%). In terms of Net Protein Ratio (NPR) and digestibility, no difference was observed between the varieties studied (p > 0.05), varying from 67.05 to 78.19%, and 78.70 to 84.88%, respectively. Diamante Negro, black and brown beans, and the Talisma beans showed 30 and 26% reduction of blood glucose, respectively, compared to the casein group but not at significant levels. No difference (p > 0.05) was observed between the varieties in terms of serum cholesterol and triacylglycerol levels. This indicates that the nutritional and functional demands of the population may be supplied by different varieties of beans.

Avaliação da qualidade protéica de uma dieta estabelecida em Quissamã, Rio de Janeiro, adicionada ou não de multimistura e de pó de folha de mandioca

O trabalho avaliou a qualidade protéica da dieta consumida por crianças desnutridas do município de Quissamã, Rio de Janeiro, e adicionada da multimistura ou do pó de folha de mandioca, utilizando 48 Rattus norvergicus, Wistar, machos, com 24 dias, pesando 58,95 g, recebendo água e ração ad libitum. Na primeira fase, denominada de Desnutrição, os animais foram distribuídos em grupo controle, alimentados com ração à base de caseína, grupo Quissamã alimentados com ração à base da dieta estabelecida em Quissamã, ambos com n=8 animais, e grupo aprotéico com n=32, recebendo uma dieta isenta de proteínas durante 10 dias. Na segunda fase, denominada de Recuperação, com duração de 18 dias, o grupo central e o grupo Quissamã permaneceram recebendo a mesma ração. O grupo aprotéico foi desmembrado em grupo desnutrido controle, alimentado com a mesma ração do grupo central e grupo desnutrido Quissamã, alimentado com a mesma ração do grupo Quissamã e mais dois grupos desnutridos recebendo a ração do grupo desnutrido Quissamã adicionada com o pó de folha de mandioca (grupo desnutrido Quissamã + folha de mandioca) e da multimistura (grupo desnutrido Quissamã + multimistura). Para o grupo controle e o grupo Quissamã foram determinados o Coeficiente de Eficácia Protéica e a Razão Protéica Líquida, nos quais o grupo controle mostrou diferenças significativas em relação ao grupo Quissamã que obteve Razão Protéica Líquida e Coeficiente de Eficácia Protéica relativos de 71,54% e 66,04%, respectivamente. Para os grupos desnutridos foi determinado Coeficiente de Eficácia Proteíca modificado, sendo o grupo desnutrido controle diferente significativamente dos grupo desnutrido Quissamã, grupo desnutrido Quissamã + folha de mandioca e grupo desnutrido Quissamã + multimistura que apresentaram Coeficiente de Eficácia Protéica relativo de 78,10%, 75,72% e 74,67% respectivamente. Conclui-se que a adição da multimistura ou do pó de folha de mandioca não causou impacto sobre a qualidade da dieta estabelecida em Quissamã, não tendo melhorado sua capacidade de recuperar a desnutrição.

Influence of feeding alkaline/heat processed proteins on growth and protein and mineral status of rats.

Effects of feeding alkaline (0.1 N NaOH) and heat treated (75 degrees C for 3 h) proteins (lactalbumin and soybean protein isolate, SPI) on growth, and protein and mineral status of rats have been determined. The untreated and alkaline/heat treated lactalbumin contained 0.10 and 4.42 g lysinoalanine (LAL)/100 g protein, respectively. Similarly, the untreated and treated SPI contained 0.03 and 1.94 g LAL/100 g protein, respectively. The formation of LAL in the treated proteins was accompanied with a loss of cystine (73-77%), threonine (35-45%), serine (18-30%) and lysine (19-20%). The alkaline/heat treatments caused significant (P < 0.05) reductions in protein digestibility of lactalbumin (99 vs. 73%) and SPI (96 vs. 68%). The processing treatments also caused a drastic negative effect on protein quality, as measured by rat growth methods such as relative protein efficiency ratio (RPER) and relative net protein ratio (RNPR). The RPER and RNPR values of untreated lactalbumin and SPI were 89-91 and 56-64%, respectively. But the RPER and RNPR values of the treated lactalbumin and SPI were 0%. The mineral status of rats was also compromised by feeding alkaline/heat treated proteins. Liver iron levels in male rats (165-180 micrograms/g dry weight) and female rats (306-321 micrograms/g dry weight) fed the treated proteins were about half the levels in male rats (229-257 micrograms/g dry weight) and female rats (578-697 micrograms/g dry weight) fed the untreated proteins. The kidney iron contents of rats fed the treated proteins were also lower than that of rats fed the untreated proteins. Liver copper levels of male and female rats fed the treated proteins were up to three fold higher than those found in rats fed the untreated proteins. The data suggested that LAL, an unnatural amino acid derivative formed during processing of foods, may produce adverse effects on growth, protein digestibility, protein quality and mineral bioavailability and utilization. The antinutritional effects of LAL may be more pronounced in sole-source foods such as infant formulas and formulated liquid diets which have been reported to contain significant amounts (up to 2400 ppm of LAL in the protein) of LAL.

The Protein Quality of Some Enteral Products Is Inferior to That of Casein as Assessed by Rat Growth Methods and Digestibility-Corrected Amino Acid Scores

Protein digestibility and quality of six enteral nutrition products sold in Canada were studied by rat balance and growth methods. Casein+L-methionine, 0.2 g/100 g diet (control) and six enteral products (freeze-dried) were fed as the sole source of protein in diets containing 8.61-9.12 g/100 g protein (N x 6.25) to weanling and 18-mo-old rats for a period of 2 and 1 wk, respectively. A protein-free diet was also included in the feeding studies to permit calculations of true protein digestibility and net protein ratio values. Values for true digestibility of protein as determined in old rats for the control diet and the test products were 95 and 89-93%, respectively. Compared with old rats, protein digestibility values were 5-7 percentage units higher in young rats. The 2-wk relative protein efficiency ratio values (42-56%) or the relative net protein ratio values (61-74%) of the enteral products were considerably lower compared to those of the control (100). Supplementation of an enteral product with cysteine, cysteine + tryptophan, cysteine + threonine or cysteine + tryptophan + threonine caused significant improvement in protein quality; suggesting that the product was limiting in these three amino acids. The protein digestibility-corrected amino acid scores for the enteral products were 43-46, 69-75 and 86-93% by using whole egg, casein and the FAO-WHO (1991) pattern as reference proteins, respectively. The results indicate that these enteral products are inferior to casein in protein quality.

Effect of amino acid supplementation on protein quality of soy-based infant formulas fed to rats

The powder forms of soy-based infant formulas obtained from four manufacturers were fed to weanling rats for two weeks, as the sole source of protein in diets containing 8% protein, 20% fat, and adequate amounts of minerals and vitamins. The relative protein efficiency ratio (RPER) and the relative net protein ratio (RNPR) values (casein + methionine = 100) of diets containing unsupplemented formulas were 71-81 and 78-85, respectively. Supplementation of the formula diets with lysine (0.2%), methionine (0.2%), threonine (0.1%) or tryptophan (0.05%) increased the level of the supplemental amino acid in rat serum but generally failed to improve the RPER or RNPR values. Addition of all four essential amino acids to the formula diets, however, caused a marked improvement in their protein quality (RPER or RNPR values = 100). The data suggested that proteins in soy-based formulas could be marginally co-limited in several indispensable amino acids.

Differences in protein digestibility and quality of liquid concentrate and powder forms of milk-based infant formulas fed to rats

Protein and amino acid digestibility and protein quality of liquid concentrate and/or powder forms of infant formulas were studied by rat balance and growth methods. Casein plus methionine (control) and eight formulas were fed to weanling rats as the sole source of protein in diets containing 8% protein (nitrogen X 6.25). Values for true digestibility of protein, lysine, methionine, or cystine (85-92%) in liquid concentrates were up to 13% lower than those in powders. Similarly, the 2-wk relative protein-efficiency ratio values (64-85%) or the relative net protein ratio values (78-94%) of liquid concentrates were up to 25% lower than those for powders. Lower levels of bioavailable lysine and methionine plus cystine in liquid concentrates compared with powders (prepared by the same manufacturer) would suggest that inferior protein quality of liquid concentrates may be due to more heat treatment involved in their preparation.

Relationship between amino acid scores and protein quality indices based on rat growth

Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR) and relative NPR (RNPR) values, and amino acid scores were calculated for 20 food products (casein, casein + Met, beef salami, skim milk, tuna, chicken frankfuters, sausage, heated skim milk, peanut butter, rolled oats, soy isolate, chick peas, pea concentrate, kidney beans, wheat cereal, pinto bean, lentils, rice-wheat gluten cereal, macaroni-cheese, and beef stew). In most cases, PER, RPER, NPR or RNPR ranked the products in the same order and positive correlations among the protein quality methods were highly significant (r = 0.98-0.99). Amino acid scores (based on the first limiting amino acid, Lys-Met-Cys, Lys-Met-Cys-Trp or lys-Met-Cys-Trp-Thr) were positively correlated to the PER, RPER, NPR or RNPR data (r = 0.61-0.75). Inclusion of the correction for true digestibility of protein improved the correlations between amino acid scores and the indices based on rat growth. The correlations were especially high between Lys-Met-Cys scores (corrected for true digestibility of protein) and PER, RPER, NPR or RNPR (r = 0.86-0.91). Inclusion of the correction for true digestibility of individual amino acids did not result in further improvements of the correlations in most cases. It is concluded that adjusting amino acid scores for true digestibility of protein would be sufficient and further correction for digestibility of amino acids would be unnecessary in mixed diets.

Protein efficiency ratios and net protein ratios of selected protein foods.

As a part of a cooperative study initiated to assess both in vitro and in vivo protein quality methods, the protein efficiency ratio (PER) and net protein ratios (NPR) of 15 different protein sources were determined. Male weanling Sprague-Dawley rats were fed a 10% protein diet. Fourteen-day NPR and relative NPR (RNPR) values and 14- and 28-day PER and relative PER (RPER) values were calculated for each protein source. When protein quality values were expressed relative to ANRC casein, the 14- and 28-day PER data ranked the protein sources essentially in the same order. RPER values of nonfat dried skim milk (unheated) and tuna were more than 100% that of casein; nonfat dried skim milk (heated), chickpeas, and breakfast sausage were between 50 and 70% of that of casein; and pinto beans and rice-wheat gluten cereal did not support substantial growth of the rat. The NPR method did not always rank the protein sources in the same order as the PER method. For the poor quality proteins, RNPR values were much higher than the RPER values; however, the RNPR and RPER values agreed closely for high quality protein sources.

Comparison of Interlaboratory Variation in Amino Acid Analysis and Rat Growth Assays for Evaluating Protein Quality

Estimates of inter- and intralaboratory variation of protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR), relative NPR (RNPR), and nitrogen utilization (NU) were compared with those of amino acid analysis in the same batches of 7 protein sources (ANRC casein, egg white solids, minced beef, soy assay protein, rapeseed protein concentrate, pea flour, and whole wheat flour). Interlaboratory variation (estimated as between-laboratories coefficients of variation, CV) of NPR and RNPR (up to 6.0%) was lower than that of PER (up to 20.2%) and RPER (up to 18.5%). The interlaboratory determination of NPR and RNPR was also more reproducible than that of most essential amino acids (CV up to 10.0%), especially tryptophan (CV up to 23.7%), cystine (CV up to 17.6%), and methionine (CV up to 16.1%). Intralaboratory variation (estimated as within-laboratories CV) of amino acid analysis (up to 4.7%), however, was comparable to that of protein quality indices in most protein sources (up to 6.0%). The significant (P less than 0.01) positive correlations (r = 0.68-0.74) between amino acid scores and protein quality indices based on rat growth were further improved when amino acid scores were corrected for digestibility of protein (r = 0.73-0.78) or individual amino acids (r = 0.79-0.82).

Inter- and Intra-laboratory Variability in Rat Growth Assays for Estimating Protein Quality of Foods

Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR), relative NPR (RNPR), and nitrogen utilization (NU) methods were investigated in an interlaboratory rat growth study. Six collaborating laboratories studied 7 protein sources (ANRC casein; minced beef; soya assay protein, SAP; pea flour; whole wheat flour, WW; rapeseed protein concentrate, RPC; and egg white solids, EW), and their 10 supplementary or complementary mixtures (casein + Met, SAP + Met, pea flour + Met, WW + Lys, WW + casein, WW + beef, WW + SAP, WW + pea flour, WW + RPC, WW + EW). Test protein(s) were added at the 8% level (N X 6.25). Casein + Met was used as the reference protein. Interlaboratory variation (estimated as between-laboratories coefficients of variation) of PER (up to 17.2%) was greater than that of RPER (up to 14.9%), NU (up to 9.5%), NPR (up to 7.0%), and RNPR, which had the lowest variability (up to 4.7%). In most cases, intralaboratory variation (estimated as within-laboratories coefficients of variation) for all the methods was less than 5%.